some values of tags in XML file are to be replaced with their corresponding Hash'ed values:ALGORITHM

[comma gene]

I have XML Files, of which some tags' values are to be anonymised.
say I will only anonymise tags <c> and <e> values.
How is this to be achieved.

I have a big XML file, around 100 MegaBytes. But number of fields to anonymise is some 5, I can set them manually in an array structure before starting processing.

 
<a>
  <b>value_of_b</b>
  <c>value_of_c</c>
  <d>
      <e attr_e_1="ae1">value_e</e>
      <f attr_f_1="af1" />
  </d>
  <g />
</a>